1. Field of the Invention
This invention relates to clips for securing together forms, and, more particularly, to clips for securing together foundation forms spaced apart a predetermined distance, and into which forms concrete is to be poured.
2. Description of the Prior Art
In typical construction, whether the construction be residential buildings or office buildings, or the like, concrete footings are usually poured into a trench dug for the specific purpose of receiving the footing. Footings are poured for the outside walls and inside bearing walls. On top of the footings for the perimeter walls is a concrete stem, typically about eighteen or more inches high. Wooden forms are first prepared into which concrete material will be poured for the stem. The forms comprise a pair of walls spaced apart a predetermined distance from each other, depending on the desired width of the stem.
There are several methods for spacing the concrete forms and for positioning the forms. One method is to use stakes driven into the ground at the outside of the forms. The stakes may be wood or metal. The forms are then supported vertically by the stakes. To insure that the forms do not spread apart at the top or at the bottom, wooden cleats may be nailed in place to insure that the form walls remain vertically oriented, or metal straps or posts may be secured to the forms for the same purpose. These staking methods obviously require a substantial amount of manual work. If wooden stakes and wooden cleats are used, additional time is required for nailing the elements together and for measuring the distances to insure that the proper width between the forms is maintained.
Another method, and one which is more economical with respect to the time involved, and more accurate, is to use clips to secure the forms together at the bottom of the forms and also at the top of the forms. An example of clip apparatus usable for this purpose is found in U.S. Pat. No. 2,973,567. The clip disclosed in the '567 patent comprises a metal strap with a pair of vertically extending and parallel end pieces. The strap and the end pieces are unitary, made of a single piece of metal, such as steel strap, with the end pieces extending from, or bent perpendicular to, the base portion. Spaced apart a predetermined distance from the end pieces are a pair of inner tabs or wings. The tabs or wings comprise angular perforations punched from the base and oriented upwardly with respect to the base portion. The forms are spaced between the respective inner tabs and end pieces. The distance between the inner tabs or wings is, of course, the width of the stem.
An alternate clip apparatus is disclosed in U.S. Pat. No. 3,547,397. The '397 apparatus discloses a clip made from wire. The clip includes a pair of parallel wire base elements with a pair of vertically extending end pieces. The clip, from the top or bottom, appears in the general configuration of a rectangle. From either end, the clip appears to be of a generally triangular configuration because the end pieces extend upwardly and inwardly at about a forty-five degree angle. The clip is preferably made of a single piece of wire. Space inwardly from the end pieces are a pair of inner supports, also made of wire. The foundation forms are disposed between the end pieces and the inner supports spaced inwardly from the end pieces.
An alternate embodiment of the '397 clip is also shown. The alternate embodiment includes a downwardly recessed portion into which the forms are disposed, which eliminates the separate wire elements spaced apart on the end pieces. In this manner the entire clip is made from a single length of wire.
Once the stem is poured, it is obvious that the clips disposed at the bottom of the forms may not be removed from the stem after the concrete is cured. Accordingly, the bottom clips remain in place and essentially are a part of the foundation. The top clips are removed to allow the forms to be removed from the partially cured concrete stem. Since roughly half of the clips are expendable, the cost of the clips becomes an item of substantial importance. Another item of importance is the weight of the clips, since the clips must be transported from the manufacturer to the distributor, and subsequently to each job or construction site. The lighter the clip, the less the freight costs.
Another consideration which is of prime importance is the ability of the clip to withstand the pressures applied by the forms in response to the force exerted on the forms by the concrete as the concrete is poured. The viscous concrete is extremely heavy and as it is initially poured, a substantial force is applied to the clips at the outer portion of the clips between the base portion and the vertically extending portion. If the clip fails, there obviously is an accompanying distortion in the form and a blow out of the concrete material. Not only must the concrete material be cleaned up as rapidly as possible, but also the forms must be re-built and the step re-poured. Both time and material are lost.
A failure of the forms which results in a blow out is usually the result of the failure of the clips to withstand a pressure surge from the concrete being poured. The surge in pressure lasts less than one second, and it must be absorbed by the forms and the clips or stakes supporting the forms. Once the surge is over, the weight of the concrete must be supported by the forms, clips, etc. The surge is a function of the height from which the concrete is poured and the weight of the concrete, in terms of vertical height. If clips fail due to the pressure surge, the blow out will either accompany the surge or will follow shortly thereafter as the weight of the concrete is hydraulically transmitted to the forms and clips. Such a situation is to be avoided, if possible.
The clip disclosed in the '567 patent, made of a single piece of strap material, such as steel strap, is relatively heavy since it is made of a solid material. The foundation clip of the '397 patent comprises parallel wires, and is lighter than the '567 clip. Since the wire of the '397 clip is duplicated or doubled, a cost factor is increased over the use of a single length of wire, as disclosed herein. Moreover, since the end pieces are a continuation of the parallel wires, no reinforcement is provided. A failure at the corners of the clip is accordingly possible without such reinforcement. The present clip is about 60% lighter than the prior art clip, patterned after the '567 apparatus, and about 25% stronger due to the end or corner reinforcing elements.
The apparatus of the present invention includes a single base element with reinforced ends. For alignment purposes, outwardly extending tabs with nail holes extending through the tabs are provided. The nail holes allow the clips to be located specifically along chalk lines outlining the stem by alignment of the tab edges along the lines. Nails are then used to secure the clips, as aligned, in place. Neither the '567 clip nor the '397 clip include any provisions for the alignment of the clips which in turn align the foundation walls. Rather, extra time must be spent in aligning the concrete forms and the clips when either the '567 or the '397 clips are used.
A further convenience with the apparatus of the present invention is color coding. Plastic end pieces, which include the tabs, are secured to the wire base and end portions. The end pieces are color coded for identification of the length of the clips for different width concrete stems and for different thickness of plywood used for the forms. Prior art clips are easily lost because they blend in with the construction residue, refuse, etc. It is also time consuming to identify clips of different sizes. These problems are overcome by the apparatus of the present invention.